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Monday, November 3, 2014

New Study Examines the Effectiveness of Collateral Vein Embolization for Non-Maturing Fistulas

Failure of a new arteriovenous fistula (AVF) may be defined as an unsuitable access site 3 months after creation. While most commonly this may be treated by balloon angioplasty, collateral vein embolization (CVE) is touted to promote maturation of a non-maturing AVF. Researchers from the University of Chicago evaluated 56 embolizations in 42 patients. The majority of patients treated by collateral vein embolization (76%) progressed to fistula maturity. In 79% of patients, this was done without angioplasty, contradicting the argument that collateral veins reflect venous outflow obstruction and do not, by themselves, indicate a true 'accessory' venous pathway. In addition, the study showed a trend toward higher rates of fistula failure in patients treated with radiocephalic fistulas undergoing CVE and PTA; however, the results were not statistically significant. Of note, fistula age, vessel, size, and number of collaterals did not correlate with the rate of fistula failure or success.

Comments:

While this study is limited by lack of objective criteria for CVE and patient sample size, the results are compelling. Unlike prior studies investigating CVE, the number of CVE procedures performed in the absence of PTA in the present study makes for a strong argument that collateral veins may represent true accessory drainage pathways that return blood to the right atrium and prevent arterialization of the target outflow vein. While more research is warranted, one may consider incorporating more aggressive treatment strategies in the setting of a non-maturing fistula.

(a) Digital subtraction angiogram in a 67-year-old man with new brachiocephalic fistula referred for fistula immaturity. Angiogram of the fistula demonstrates a large collateral vein arising from the primary venous outflow (arrow) without other diagnostic abnormality. This vessel was subsequently selected, and embolization was performed with four 0.035-inch, 8-mm pushable coils. (b) Postembolization image after CVE no longer demonstrates opacification of the collateral vessel.